At the present time, there are basically three nongovernment manufacturers of propellant powders: Winchester Group of Olin Corporation, Hercules, and DuPont. Hercules and DuPont make extruded powders while Olin makes oblate spheroid powders. In addition to making powder, Olin (dba Winchester) and DuPont (dba Remington) are the world's leading commercial ammunition manufacturers. In addition, the U.S. Government has oblate spheroid powder operations and ammunition plants, and the U.S. Government probably has the most advanced ammunition research facilities in existence anywhere. Out of these government research facilities came a program to develop an improved 7.62mm cartridge capable of increased armour penetration. One proposal was to use a saboted, light armour penetrator at ultra high (greater than 4,000 feet per second) velocity with spin stabilization. However, these advanced government research facilities, having a design, were unable to make it work. Sabot breakup occured in the barrel and yet sabot changes such as a washerlike force multiplier in the sabot base did not solve the problem. Since the U.S. Army is currently carrying, as standard issue, 7.62mm rifles, it is of major importance to solve the problem and thus give the infantryman a better chance against lightly armoured targets. For this proposed 7.62 mm SLAP round the government specified WC680 powder, an oblate spheroidal powder made by Olin at St. Marks, Fla.
It is well recognized that:
Present 7.62 mm ammunition cannot penetrate light armour.
The service presently has 7.62 mm guns in action as standard issue.
Serious consideration to switching to 5.56 mm guns and 5.56 mm ammunition in view of equivalent penetration and long-range ability demonstrated by such 5.56 mm candidates at the SS109 made by FNH of Belgium and "Winchester" of U.S.A.
The service has an obvious preference to develop enhanced 7.62 mm ammunition that has the ability to penetrate light armour in order to avoid an expensive switch to lighter 5.56 mm ammunition with the resultant requirement of a switch over of virtually all existing combat guns. Also, the 7.62 mm is a bigger, heavier round and would thus be expected to out-distance enemy 5.56 mm rifles and to penetrate more armour or do more damage to a target given equal penetration.
In view of the need of America for successful solution of this problem, Winchester undertook independent effort to solve these problems which had baffled the foremost military ammunition experts.
The results at Winchester with the present invention were stunning. A particular experimental powder mix was found to solve both sabot breakup and low velocity, resulting in the first successful 7.62 mm light armor penetrating round; one which, on test, penetrates the armour (both sides) of simulated Russian armoured personnel carriers. The round thus gives the 7.62 mm rifles the heretofore absent ability to defeat current light armour plate and may well help prevent the service from having to switch over to 5.56 mm hardware. To put it graphically, it is believed that this round has enough penetrating ability to knock apart the treads of current Russian tanks by shots fired from current infantry carried guns. Furthermore, the 7.62 mm SLAP, with use of the invention, has superior penetrating ability to that of any currently available 5.56 mm round.
The invention is also suitable for scale-up into 0.50 caliber rounds with the probable ability to defeat medium armour plate using the widely available 0.50 caliber machine guns.
The inventon solves these problems by providing the round with a propellant charge of high loading density (volumetric) consisting essentially of spherical propellant particles. At least about 95% preferably have a grain diameter within the range of from about 0.082" to about 0.0232", and an average grain diameter within the range of from about 0.0145" up to about 0.0170".